Two speed transmission and belt drive system

ABSTRACT

A two speed transmission and belt drive system utilizing the transmission. The two speed transmission comprises a planetary gear train comprising an input pulley connected to an input carrier, and a sun gear and a ring gear. The input carrier also comprises a plurality of planetary gears disposed between the sun gear and the ring gear. The sun gear is engaged with an electromagnetic brake member. The ring gear is engaged with an output pulley. A one-way clutch is disposed between the input carrier and the output shaft. The brake member is engaged at engine idle and is disengaged at engine speeds above idle. When the brake member is engaged the sun gear does not rotate, thereby driving the ring gear and output pulley at a greater speed than the input pulley. An accessory pulley operates with the transmission output pulley resulting in an accessory speed that is proportional to an engine speed at idle. At engine speeds above idle the transmission is disengaged and the output pulley to accessory pulley ratio drives the belt driven accessory at a speed less then an engine speed. An accessory can also be directly connected to the output shaft in conjunction with the output pulley. The transmission can be used with a motor generator system by providing a speed reducing unit disposed between an engine and the motor generator.

FIELD OF THE INVENTION

The invention relates to a two speed transmission and belt drive system,more particularly, to a vehicle engine belt drive system using acombination of accessory pulleys and a two speed transmission having anelectromagnetic brake. The two speed transmission output pulley incombination with each accessory pulley drives engine accessories at afirst speed substantially proportional to an engine speed at engine idleand proportionally less than the first engine speed for those enginespeeds substantially greater than an engine idle speed. The transmissionalso provides a speed reducing unit disposed between an engine and amotor generator.

BACKGROUND OF THE INVENTION

Vehicle engines generally comprise certain accessories that are used inthe operation of the engine and vehicle. Such accessories can include apower steering pump, an air conditioning compressor, an alternator, anoil pump, a fuel pump and so on. These accessories are generally drivenby a serpentine belt. The serpentine belt engages a pulley on eachaccessory as well as on an engine crankshaft. The engine crankshaftprovides the torque to drive the accessories.

As the belt is driven by the crankshaft it is necessarily subject toengine speed variations during acceleration and deceleration of thevehicle. In other words the operating speed of the accessories isdirectly proportional to the speed of the engine. The variations inengine speed, particularly engine speeds greater than idle, result ininefficient operation of the accessories because each accessory must bedesigned to operate satisfactorily over the entire engine speed range.This necessarily means that the efficiency is less than optimum for mostof the engine speed range. Therefore it is desirable to decouple some orall of the accessories from the engine crankshaft so they can be drivenat a lower and narrower optimum speed range. Further, operating theaccessories at relatively higher speeds places a greater load on theengine than if they are operated at a slower speed.

Representative of the art is U.S. Pat. No. 4,862,770 (1989) to Smithwhich discloses a two-speed gear box adapted to be mounted on the faceof an automobile accessory, such as an automotive alternator to increasethe speed of the alternator on demand.

The clutch assembly disclosed in Smith comprises a brake bandencompassing an outer cylindrical surface. The brake band is operatedwith mechanical vacuum means which engage or disengage the brake band.Such a system can be adversely affected by loss of vacuum, for exampleby vacuum hose failure, or by contamination on the cylindrical surfacebetween the brake band and the cylindrical surface.

The prior art transmissions are designed to proportionately reduce thespeed of the driven accessories as the engine speed increases aboveidle. This reduces the accessory power requirement. However, at idle theaccessories are operated on a 1:1 basis with no speed reduction ascompared to engine speeds above idle.

In recent years, an automatic engine stopping and starting apparatus hasbeen known for stopping an engine after a running vehicle has beenstopped and restarting the engine if conditions for driving the vehiclehave been satisfied again. The automatic engine stopping and startingapparatus is arranged such that fuel supply to the engine is interruptedwhile the vehicle is stopped, resulting in reduced fuel consumption.

Representative of the art is U.S. Pat. No. 6,048,288 (2000) to Tsujii etal. which discloses a system that operates a motor when a vehicle isstopped by providing a connection switching unit disposed between thedrive shaft of the engine and a rotational shaft of the motor toenable/disable power transmission between the drive shaft of the engineand the rotational shaft of the motor, and a transmission controllerthat controls a function of the connection switching unit forenabling/disabling power transmission. When an auxiliary machine isoperated by a motor while the engine is stopped, control is performedsuch that rotation of the rotational shaft of the motor is nottransmitted to the drive shaft of the engine. The auxiliary machine isoperated by the motor without operating the engine.

What is needed is a belt drive system that controls an accessory speedwith respect to an engine speed by a combination of a two speedtransmission ratio and output pulley and accessory pulley ratio. What isneeded is a two speed transmission comprising an electromagnetic brakecontrolled with respect to an engine condition. What is needed is atwo-speed transmission having coaxial input and dual outputs. What isneeded is a motor generator system that has a speed reducing unitdisposed between the engine and a motor generator. The present inventionmeets these needs.

SUMMARY OF THE INVENTION

The primary aspect of the invention is to provide a belt drive systemthat controls an accessory speed with respect to an engine speed by acombination of a two speed transmission ratio and output pulley andaccessory pulley ratio.

Another aspect of the invention is to provide a two speed transmissioncomprising an electromagnetic brake controlled to an engine condition.

Another aspect of the invention is to provide a two-speed transmissionhaving coaxial input and dual outputs.

Another aspect of the invention is to provide a motor generator systemthat has a speed reducing unit disposed between the engine and a motorgenerator.

Other aspects of the invention will be pointed out or made obvious bythe following description of the invention and the accompanyingdrawings.

The invention comprises a two speed transmission and belt drive systemutilizing the transmission. The two speed transmission comprises aplanetary gear train comprising an input pulley connected to an inputcarrier, and a sun gear and a ring gear. The input carrier alsocomprises a plurality of planetary gears disposed between the sun gearand the ring gear. The sun gear is engaged with an electromagnetic brakemember. The ring gear is engaged with an output pulley. A one-way clutchis disposed between the input carrier and the output shaft. The brakemember is engaged at engine idle and is disengaged at engine speedsabove idle. When the brake member is engaged the sun gear does notrotate, thereby driving the ring gear and output pulley at a greaterspeed than the input pulley. An accessory pulley operates with thetransmission output pulley resulting in an accessory speed that isproportional to an engine speed at idle. At engine speeds above idle thetransmission is disengaged and the output pulley to accessory pulleyratio drives the belt driven accessory at a speed less then an enginespeed. An accessory can also be directly connected to the output shaftin conjunction with the output pulley. The transmission can be used witha motor generator system by providing a speed reducing unit disposedbetween an engine and the motor generator.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthe specification, illustrate preferred embodiments of the presentinvention, and together with a description, serve to explain theprinciples of the invention.

FIG. 1 is a cross-sectional view of the two speed transmission.

FIG. 2 is a cross-sectional view of the two speed transmission.

FIG. 3 is a perspective view of the planetary gear carrier.

FIG. 4 is a partial perspective view of the planetary gears on thecarrier.

FIG. 5 is a partial perspective view of the planetary gear bearings andcarrier bushings.

FIG. 6 is a partial perspective view of the carrier and output pulley.

FIG. 7 is a partial perspective view of the carrier and output pulleyand input pulley.

FIG. 8 is a partial perspective view of the carrier brake shoe andoutput pulley.

FIG. 9 is a partial perspective view of the bearings and carrier brakeshoe.

FIG. 10 is a perspective view of the transmission with the coil.

FIG. 11 is a cross-sectional view of the two speed transmission with analternator connected to the transmission and coupled to the outputshaft.

FIG. 12 is a schematic of a belt driven accessory drive.

FIG. 13 is a schematic of the inventive transmission used in a generatormotor application.

FIG. 14 is a schematic of the inventive transmission in an alternategenerator motor arrangement.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a cross-sectional view of the two speed transmission. The twospeed transmission 100 is used on a belt driven accessory drive of thetype used on vehicle internal combustion engines. It may also be used inany application where a two speed transmission is needed, for example,for driving industrial equipment or as a transmission on a 2, 3 or 4wheeled vehicle.

The transmission and associated control system automatically control anaccessory speed based on engine speed in order to optimize engine fuelefficiency and available output drive torque at the drive wheels. Thetransmission is very compact and can be mounted directly on anaccessory, for example on a power steering pump, alternator or airconditioner compressor. In this arrangement the accessory is connectedto an engine block.

The two speed transmission 100 comprises planetary gears disposed on aninput carrier. The transmission input shaft and output shaft arecoaxial. An electromagnetic brake is used to control sun gear rotationand, thereby, output shaft speed.

An endless power transmission belt is drivingly engaged between a driverpulley such as an engine crankshaft CR, see FIG. 12, and a transmissioninput pulley 10. The belt may comprise a v-belt or multiple-ribbed belt,each known in the art. The belt may be replaced by a by a chain ortoothed belt each know in the art.

Input pulley 10 is connected to the input carrier using fasteners knownin the art. The input carrier comprises input carrier portion 11 andinput carrier portion 20 which is disposed opposite input carrierportion 11, planetary gear members 15, and input shaft 200. A pluralityof shafts 21 interconnect between portion 11 and portion 20. Eachplanetary gear member 15 is journalled to a shaft 21. Input carrierportion 20 is connected to input shaft 200.

Labyrinth seal 26 is connected to output pulley 30. O-ring seal 25 isdisposed between shaft 19 and input carrier portion 11. Each seal isknown in the art and prevents debris from entering the planetary gearset.

Ring gear 17 and sun gear 18 each have a gear mesh engagement withplanetary gears 15. Sun gear 18 is disposed on shaft 19. Ring gear 17 isdisposed on the output pulley 30. Shaft 19 rotates concentrically aboutinput shaft 200 and output shaft 31. Planetary gears 15, sun gear 18 andring gear 17 comprise straight cut gears. Use of straight cut gearsnegates the need for thrust bearings which might otherwise be neededwith helical type gears. This significantly reduces the cost of theplanetary gear train.

Brake 40 comprises a housing 52, an electromagnetic coil 41 and anaxially moveable brake shoe 190 for frictional rotation stoppingengagement. Brake shoe 190 of shaft 19 frictionally engages coil 41 whencoil 41 is electrically activated, thereby stopping rotation of sun gear18.

Input shaft 200 is journalled to brake housing 52 on bearings 23, 24.Bearings 23, 24 comprise ball bearings known in the art and are used toprovide a proper support for brake 40. Other bearings known in the artmay also be used, for example, needle or cone bearings.

Brake 40 is electromagnetically actuated to engage and stop rotation ofportion 190 and thereby shaft 19 and sun gear 18 based upon an enginespeed signal. Brake 40 is either engaged (shaft 19 stopped) ordisengaged (shaft 19 rotates). Brake 40 is engaged at engine idle anddisengaged for engine speeds above idle. Power is provided to the brake40 coil by wires 410 from a vehicle electrical system, and may either be12V or 42V or some other desired voltage.

Retainer clips 230, 231 and 240 retain bearings 23, 24 in place on inputshaft 200. The clips also keep input shaft 200 properly spatiallylocated with respect to brake housing 52.

Shaft 19 is journalled to input shaft 200 on sleeve bearing 50. A sleevetype bearing is sufficient for this service because the radial loads areminimal at idle when brake 40 is engaged, i.e., input shaft 200 isrotating and shaft 19 is locked up. At speeds greater than idle, brake40 is disengaged and shaft 19 rotates in unison with input shaft 200 byoperation of the one-way clutch 22, i.e., there is no differentialrotation between shafts 19 and 200. Housing 52 can be mounted to anengine block or other mounting surface using known fasteners such asbolts, screws or studs engaged through bosses 53, 54.

One-way clutch 22 is disposed between input shaft 200 and output shaft31. One-way, or sprag, clutch 22 is of a type known in the art, forexample, a model GFK 5904 available from Warner Electric/Formsprag.

Planetary gears 15, belt bearing surface 33, bearing 50, and one-wayclutch 22 are substantially coplanar in a radial direction with respectto an axis of rotation A-A. This arrangement has the benefit ofminimizing or eliminating bending moments that might be imposed on theoutput portion of the transmission caused by a more axially staggeredarrangement.

End 32 of output shaft 31 allows an accessory to be directly connectedto the output shaft 31. End 32 can be used with any form of couplingknown in the art, for example, keyed, keyless or splined. The accessoryis directly connected to housing 52 using known fasteners, for example,bolts or screws, see FIG. 11. The accessory can comprise an alternator,air conditioner compressor, power steering pump, fuel pump, oil pump orany other rotary accessory. The directly coupled accessory is driven atthe same speed as the output pulley 30.

Output pulley 30 engages an endless power transmission belt whichtransmits torque to other belt driven accessories in a belt drivesystem, see FIG. 12.

In operation a power transmission belt B1 engaged with a driver such asa crankshaft pulley CR transmits torque to input pulley 10. Thetransmission output pulley 30 then transmits torque through a secondendless belt B2 which is drivingly connected to other belt drivenaccessories.

The transmission operates in one of two modes based upon engine speed.Brake status is a function of engine speed, i.e., the output pulleyspeed is determined in part by whether the brake is engaged ordisengaged.

When brake 40 is engaged shaft 19 is held stationary with respect to thetransmission housing, that is, shaft 19 does not rotate. Hence, sun gear18 does not rotate. The input carrier drives planetary gears 15 onstationary sun gear 18. Rotation of the planetary gears 15 in turndrives ring gear 17 which in turn drives output pulley 30 and outputshaft 31. The input/output pulley speed increase ratio in this mode isin the range of approximately 1.1 to 3.0 depending upon the relativediameters of the sun gear and ring gear. The preferred transmissionratio is in the range of approximately 1.3 to 1.8, although ratiosoutside this range are available for use if required by a particularsystem. The transmission ratio is the ratio of the transmissionplanetary gear set only and is independent of the pulley ratios,including the pulley ratio between the output pulley and the accessorypulley, as well as the ratio between the crankshaft CR pulley and theinput pulley 10.

In a first operating mode brake 40 is engaged when the engine is startedor operating at an idle speed. The brake is electrically engaged ordisengaged by an engine speed signal provided by an engine control unit500. Unit 500 may be formed as a computer system provided with knownunits including a CPU, a RAM, a ROM, a bi-directional communication bus,interface circuits (a signal conversion circuit and the like), and amemory. Unit 500 receives an engine speed signal from an sensor orinstrument such as a tachometer 600, or other similar instrument fordetecting rotational velocity known in the art such as a proximitydetector.

When the engine is shut off, brake 40 is not engaged. When a key isinserted to start the engine, brake 40 is activated before the starterstarts the engine. However, to ease the engine start, brake 40 can beactivated slightly after the engine is running. In this case the one-wayclutch drives the output shaft and the accessories are driven at a lowerspeed than required for idle, thereby minimizing the engine start powerrequirement. When the brake is disengaged the accessories are driven ata slower speed due to the pulley ratio between the output pulley 30 andan accessory pulley as described herein. The time delay between enginestart and brake activation is approximately 0.5 to 1.0 seconds. Afterthe time has elapsed brake 40 is engaged. More particularly, at enginestart, or, as the engine speed slows below a desired level, for exampleapproximately 1200-1500 RPM, the speed signal detected by an enginecontrol unit 500 generates a control signal. The control signalactivates the brake thereby stopping rotation of sun gear 18. As noted,this results in the output shaft 30 being driven through the planetarygears at a greater rotational speed than the driven input shaft 10. Ofcourse, the engine speed at which brake 40 is activated is selectedbased upon the nature of the engine and its desired operatingcharacteristics.

In this description the engine idle speed is approximately 800 RPM. Thetransition speed at which the brake is engaged or disengaged isapproximately 1200-1500 RPM so that the accessory speed does not dropsignificantly below a minimum desired speed at idle, thereby avoidingthe situation where the accessory or accessories are driven too slowly,even if only momentarily.

The second operating mode is when the engine is running at speedsgreater than engine idle, for example at cruise or otherwise in excessof a pre-selected engine speed for example 1200-1500 RPM. Once theselected speed is detected by unit 500, brake 40 is disengaged. With thebrake disengaged, shaft 19 is unlocked and sun gear 18 rotates in unisonwith the input carrier. One-way clutch 22 is engaged thereby drivingoutput shaft 31 on a 1:1 basis with the input shaft 200.

However, the transmission ratio is only a part of the overall system bywhich the belt driven accessory drive speed is determined. Therotational speed of each accessory is also individually determined inpart by the diameter of the accessory pulley and its ratio with respectto the output pulley 30. Therefore, the final belt driven accessoryspeed for a given engine speed is a function of the driver pulley(crankshaft) diameter, input pulley 10 diameter, transmission ratio,output pulley diameter 30, and the accessory pulley diameter. Each ofthese variables are selected and combined to give the desired finaldrive ration and hence belt driven accessory speed. The final driveratio determines the accessory speed for a given crankshaft (engine)speed.

In an exemplary accessory drive system, it is estimated that theinventive transmission can provide fuel savings on the order of up toapproximately 5% compared to a comparable engine without thetransmission. The inventive system at engine speeds greater than idledecreases the rotational speed of the accessories. This improves engineand vehicle performance, including improved acceleration times andincreased power available at the drive wheels.

In an exemplary system using a 2.0 L engine, the inventive system hasthe following operating characteristics. 2.0 L Engine (Comparison:Original (Prior Art) and Transmission) Pulley Accessory Speeds AccessorySpeeds Diameters (mm) (RPM) - “Idle” (RPM) - “Off Idle” Two Two TwoOriginal Speed Original Speed Original Speed Drive Module Drive ModuleDrive Module Crank 134.01 111.98 800 800 2500 2500 AC 146.01 N/A 734 7342295 1458 PS 139.51 138.03 767 767 2402 1536 Alt 56.86 56.86 1866 18665833 3705 WP 107.50 106.38 998 998 3118 1981 Input N/A 192.00 N/A 467N/A 1458 Output N/A 144.50 N/A 734 N/A 1458

In the first column the diameter in mm is given for each pulley as usedon an original drive and on a drive system using the two speedtransmission (two speed module). The nomenclature is as follows:“Crank”—crankshaft, “AC”—air conditioner, “PS”—power steering,“Alt”—alternator, “WP”—water pump. In this example system the airconditioner (AC) is directly connected to the output shaft 31 of thetransmission, however, this is not intended to be limiting since any ofthe accessories may be directly connected to output shaft 31. At anengine speed referred to as “idle” for ease of reference, the two speedtransmission is engaged, that is, brake 40 is engaged. “Idle” in thisexample is arbitrarily set at approximately 800 RPM. The transmissionratio is approximately 1.57. At idle the speed of the accessories asdriven by the two speed transmission is the same as a proportional“original drive”. An “original drive” is a prior art drive directlyengaged with the crankshaft without a two speed transmission.

At an engine speed greater than idle, in this example 2500 RPM, brake 40is disengaged. Therefore, one-way clutch 22 is operational resulting ininput pulley 10 and output 30 pulley rotating in unison. Input pulley 10and output pulley 30 each rotate at 1458 RPM. However, due to the pulleydiameter for each accessory, one can see that each accessory rotates ata relatively slower speed as compared to the original prior art system.In this and the following example at idle, the pulley diameters areselected so that the respective pulley ratio between the output pulley30 and each accessory pulley effectively negates the 1.57× relativespeed increase caused by the transmission when brake 40 is engaged.

The final drive ratio in the 2.0 L engine example for the alternator atengine idle is approximately 2.33 (1866 RPM/800 RPM). At the “off idle”engine speed the final drive ratio for the alternator is approximately1.48 (3705 RPM/2500 RPM). The inventive system imparts a final driveratio for a belt driven accessory that is inversely related to enginespeed. The inverse relationship of a pulley drive ratio to engine speedalso applies to the accessory directly connected to and driven by thetransmission, namely, the crankshaft pulley and the transmission inputpulley.

At engine speeds greater than idle, the inventive system is given fullreign when the brake 40 is disengaged and one-way clutch 22 is locked.The input 10 and output 30 pulleys rotate in unison. This combined withthe accessory pulleys decreases the accessory rotational speed ascompared to a prior art system. Reducing the accessory speed in thismanner significantly increases overall fuel efficiency of the engine. Italso increases torque available to the drive wheels. Of course, thepulley ratios can be selected to accommodate any engine accessory driveconfiguration.

In another example, a 5.3 L engine system is illustrated. 5.3 L Engine(Comparison: Original (Prior Art) and Transmission) Pulley DiametersAccessory Speeds Accessory Speeds (mm) (RPM) - “Idle” (RPM) - “Off Idle”Two Two Two Original Speed Original Speed Original Speed Drive ModuleDrive Module Drive Module Crank 193.57 193.57 650 650 1500 1500 AC 111.9N/A 1124.5 1124.5 2595 1648 PS 163.6 187.19 769 769 1775 1127 Alt 59.3167.8 2121.6 2121.6 4896 3110 WP 150.8 172.46 834.6 834.6 1926 1223 InputN/A 176.13 N/A 714.4 N/A 1648 Output N/A 128 N/A 1124.5 N/A 1648

In this example, the transmission ratio is also approximately 1.57. Theidle speed in this example is approximately 650 RPM as compared to 800RPM for the previous example. The final drive ratio in this example forthe alternator at engine idle is approximately 3.26 (2121.6 RPM/650RPM). At the “off idle” engine speed the final drive ratio for thealternator is approximately 2.07 (3110 RPM/1500 RPM).

In each example, with respect to the A/C which is directly connected tooutput shaft 31, the directly connected accessory speed at engine idlecorresponds to the pulley ratio between the crankshaft pulley and theinput pulley 10 as modified by the transmission ratio. At engine speedsin excess of engine idle the directly connected accessory speedcorresponds to the pulley ratio between the crankshaft pulley and theinput pulley 10. At engine speeds above idle there is no additionaleffect due to the transmission ratio since the planetary gears are notoperable and all rotation of the output shaft is caused by the one-wayclutch 22.

The duty cycle for the transmission in the inventive system isapproximately 5%, meaning the transmission is in operation (that is,brake engaged) approximately 5% of the time, basically when the engineis at idle. The duty cycle is dependent on the engine operatingconditions and is preferably in the range of approximately 4% to 10% andmay be as high as approximately 25% or 30%. On the other hand the priorart systems have a reciprocal duty cycle (˜95%) since they operate atransmission when the engine is operated at speeds greater than idle. Alow duty cycle is desirable because it extends the operating life of thetransmission. It should again be understood that the term idle is usedfor ease of reference and is not intended to signify limiting theinvention to particular engine speed. Idle speed can and does differamong various vehicles and engine types.

The system allows multiple accessories to be driven at two differentspeeds for any range of engine speeds. This first available accessoryspeed being that of the accessory which is directly connected to theoutput shaft 31. The second accessory speed being that of the beltdriven accessory as further determined by the transmission ratio andrespective pulley ratio of the transmission output pulley 30 and aparticular driven accessory pulley.

The accessories can be selected and located in a belt drive system tooptimize the beneficial effect of two available operational speeds. Forexample, the air conditioner or alternator can be directly connected tothe transmission output shaft (32) while other belt driven accessories,such as a power steering pump or water pump, are driven at a differentspeed by a second belt from the output pulley 30.

The innovative compact design is realized by disposing the planetarygear train fully within the width (W) of the belt bearing portion 33 ofthe output pulley 30. Brake shoe 190 for the sun gear 18 is compactlydisposed adjacent the input pulley 10. Hence the overall thickness ofthe transmission is substantially a function of the width of the pulley10, pulley 30 and the width of brake 40. Depending upon electricalservice requirements, conditions, brake 40 can be fully contained withina width (W2) of input pulley 10. Hence, the overall thickness of thetransmission has a lower limit substantially bounded by the width of theinput and output pulley in the closest possible proximity. For example,this can represent an overall end-to-end transmission thickness as smallas approximately 45 mm. Assuming that at least a single belt width is agiven in front end accessory drives, the inventive transmission allows asignificant increase in fuel efficiency while only requiring an extraclearance space on the order of approximately 30 mm, and in certaincases less than 20 mm is required based on the overall width of anoutput belt B2.

FIG. 2 is a cross-sectional view of the two speed transmission. Inputcarrier portion 11 and input carrier portion 20 are connected togetherwith members 27 by fasteners 201. Members 27 are circumferentiallydisposed about the input carrier, see FIG. 4. Input pulley 10, inputcarrier portion 11, input carrier portion 20 and input shaft 200comprise an input rotating assembly. As described in FIG. 1 planetarygears 15 are journalled to the input carrier shafts 21. When brake 40 isdisengaged, one-way clutch 22 is engaged and thereby drives output shaft31. When brake 40 is engaged one-way clutch 22 is disengaged sinceoutput shaft 31 is rotating as a speed greater than the speed of inputshaft 200.

FIG. 3 is a perspective view of the planetary gear carrier. Planetarygears 15 are disposed circumferentially about the carrier alternatelyinterposed between members 27. Fasteners 201 connect portion 11 tomembers 27.

FIG. 4 is a partial perspective view of the planetary gears on thecarrier. Each planetary gear 15 is journalled to a shaft 21 on a bearing210 known in the art, such as a needle bearing or sleeve bearing. Thebearing selection is dependent on the service conditions.

FIG. 5 is a partial perspective view of the planetary gear bearings andcarrier sleeve bearing. Each planetary gear bearing 210 is disposedbetween a planetary gear 15 and a shaft 21. Carrier sleeve bearing 50 isdisposed between input shaft 200 and output shaft 31.

FIG. 6 is a partial perspective view of the carrier and output pulley.The compact design of the transmission allows the planetary gear carrierto be fully contained within a width of the output pulley. Input shaft200 comprises a bore 202 in which output shaft 31 is disposed.

FIG. 7 is a partial perspective view of the carrier and output pulleyand input pulley. Fasteners 12 attach input pulley 10 to input carrierportion 11. Input pulley 10 may also be attached to input carrierportion 11 by tack welding or any other suitable connecting means knownin the art.

FIG. 8 is a partial perspective view of the carrier brake shoe andoutput pulley. Brake shoe 190 comprises a radially extending surfacewhich frictionally engages coil 41 upon activation of said coil.Engagement of shoe 190 with coil 41 stops rotation of the sun gear 18.Brake shoe 190 is substantially contained within a width of input pulley10.

FIG. 9 is a partial perspective view of the bearings and carrier brakeshoe. Bearings 23, 24 support input shaft 200 on brake housing 52.

FIG. 10 is a perspective view of the transmission with the coil. Brake40 axially locates and supports input shaft 200 on bearings 23, 24.Bosses 53, 54 are used with fasteners to connect the transmission to amounting surface.

FIG. 11 is a cross-sectional view of the two speed transmissionconnected to an alternator 700. Alternator 700 is directly coupled tothe output shaft 31. Alternator 700 is simply used as an example as anyother accessory may be directly connected to the transmission as well.Direct coupling is accomplished by use of splines 703 on shaft 31,although any form of shaft coupling suitable for the service and knownin the art is acceptable.

Tabs 702 extend from the transmission and alternator. Fasteners 701connect tabs 702. Fasteners 701 comprise screws, bolts or studs forexample. Alternator 700 is electrically connected to a vehicleelectrical system in a manner known in the art.

FIG. 12 is a schematic of a belt driven accessory drive. Belt B1 isdrivingly engaged between a crankshaft pulley CR and input pulley 10.Belt B2 is drivingly engaged between output pulley 30 and accessorypulleys A2 and A3. Belt B1 and B2 each comprise a multiple ribbedprofile, see FIG. 2. An accessory A1 is directly coupled to thetransmission 100. Accessory A1 may comprise an alternator 700. A belttensioner T imposes a tension on belt B2. Tensioner T may comprise anytensioner known in the art, including an asymmetric tensioner, Zed type,or linear tensioner.

The asymmetric tensioner comprises a pulley pivotally mounted to atensioner arm. The asymmetric tensioner comprises a damping mechanismthat has a damping force which is greater in a first direction than in asecond direction.

In an alternate embodiment, either belt, B1 or B2 or both, used in theinventive system comprises a low modulus belt known in the art. The lowmodulus belt comprises a belt having a tensile cord comprising nylon 4.6or nylon 6.6 or a combination of the two. An elastic modulus of the beltis in the range of approximately 1500 N/mm to approximately 3000 N/mm. Afeature of the low modulus belt is that it can be installed on a beltdrive system without a tensioner or moveable shaft accessory. The lowmodulus belt is simply installed using a belt installation tool known inthe art. The tool is used to roll or laterally urge the belt over anedge of a transmission pulley or accessory pulley without the need tootherwise adjust the center location of the pulley shaft. The lowmodulus belt is particularly suitable for belt B1 since equipping thetransmission in such a way that it would otherwise be movable to allowinstallation and adjustment of belt B1 might be more expensive thansimply designing the transmission to be directly connected to an enginemounting surface such as an engine block. Further, adjusting thetransmission shaft location with respect to the crankshaft would consumemore assembly time as well.

In yet another embodiment chains may be used in place of the belts.

Of course, transmission 100 and one or all of the accessories may alsobe provided with adjustable mounting means known in the art which allowsthe shaft location to be adjusted during installation.

FIG. 13 is a schematic of the inventive transmission used in a generatormotor application. Automatic transmission (“A/T”) 2 is disposed adjacentto the engine (“E/G”) 1. Motor generator 300 (“M/G”) serves as a motorand an electric generator. Engine crank shaft 3, and shaft 31 and shaft200 of the M/G 300 are disposed in parallel with each other. M/G 300 isdirectly connected to transmission 100 as described elsewhere in thisspecification. Transmission 100 is mechanically disposed between the M/G300 and the crank shaft 3 so that the rotational speed of shaft 200 isreduced and transmitted to crank shaft 3. Pulley CR is connected to thecrank shaft 3. Pulley 10 is connected to transmission 100 as describedin this specification. Belt B1 is set between pulley CR and pulley 10.Pulley 30 is directly connected to shaft 31 of the M/G 300. Pulley 10 isoperatively connected to shaft 200 by the planetary gear set.

Pump P for a power steering unit and a compressor A/C for an airconditioner are each an accessory included in the engine belt drivesystem. Pulleys A2 and A3 are secured to the respective ends of therotational shafts of the pump P and the compressor A/C. A belt B2 isengaged among the pulleys 30, A2, and A3. The pulleys 30, A2, A3 and thebelt B2 constitute a power transmission means for transmitting rotationof M/G 300 to the respective accessories.

An inverter 400 is electrically connected to M/G 300 and arranged tovary the amount of electric energy to be supplied from a battery 800 tothe M/G 300 to control the speed of M/G 300 when M/G 300 is used in amotor mode. Inverter 400 also performs control to store electric energygenerated by M/G 300 to battery 800.

M/G 300 is connected to an oil pump 194 for the A/T throughelectromagnetic clutch 191. An oil inlet pipe 192 is connected to theoil pump 194. An oil outlet pipe 193 is connected to the oil pump 194.Oil pimp 194 is connected to an engine lubrication system (not shown).The foregoing structure enables M/G 300 to operate the oil pump 194 byengaging electromagnetic clutch 191 while the engine is stopped. This isbecause the starting clutch (not shown) disposed in the A/T is arrangedto be immediately engaged for driving the vehicle smoothly upon re-startof the engine.

Referring again to FIG. 13, controller 500 transmits to inverter 400 asignal for controlling the engine running mode switching operation,ON-OFF control signals to the electromagnetic clutch 191 and ON-OFFcontrol signals to the electromagnetic coil 41 of the transmission.Controller 500 also receives signals from various sensors disposed onthe vehicle and on the engine that are indicative of a vehicle operatingcondition and/or of an engine operating condition. These include asignal indicating the speed of M/G 300, a signal for switching theengine running mode, a signal for switching the operation of the airconditioner, an engine status signal indicating, for example, the speedof the engine 1, a vehicle status signal (not shown) indicating thevehicle speed and the like, a wheel brake status signal, an enginethrottle position signal, and a status signal of the A/T indicating therange selected by the shift lever. The brake status signal indicates thestate of engagement of each wheel brake or all wheel brakes on thevehicle. The throttle position signal relates to the position of thethrottle, which is indicative of the driver demand to the engine such asacceleration, deceleration, non-accelerating cruise or idle. Each signalmay be either analogue or digital.

In accordance with information indicated by the above-mentioned signalscontroller 500 performs an operation for reading data from a memory 900and a calculating operation to determine an engine first running mode(engine operating) or a second running mode (engine not operating). Thencontroller 500 transmits control signals to the transmission brake coil41, the inverter 400, and electromagnetic clutch 191. Controller 500 maybe formed as a computer system provided with known units including aCPU, a RAM, a ROM, a bi-directional communication bus, interfacecircuits (a signal conversion circuit and the like), and a memory 900.

The operation will now be described. Initially, M/G 300 is operated tostart the engine 1. After starting the engine 1, M/G 300 acts as a powergenerator for storing electric energy in the battery 800. When theengine is started, the controller 500 detects the speed of M/G 300.Moreover, controller 500 causes inverter 400 to perform a switchingoperation such that a torque and speed required to start the engine 1are realized. For example, if a signal for switching the air conditionerA/C has been turned ON at engine start, a higher torque is requiredcompared with the OFF state of the A/C. Therefore, controller 500applies to inverter 400 a switching control signal to allow M/G 300 torotate at a higher torque with a greater speed.

The switching control signal may be determined such that a variety ofstatus signals of the engine 1, the A/T 2 and the vehicle are providedto the controller 500 and thereby collated with a map memory stored inthe memory. Alternatively, the switching control signal may bedetermined by calculations performed by the processor unit (CPU)disposed in controller 500.

When an engine stop signal is turned ON controller 500 stops the engine1 by transmitting a signal for interrupting fuel supply to the engine 1for example to an electric fuel pump (not shown). The engine stopoperation can be performed under a condition where, for example, thevehicle speed is zero, the brakes are partially or fully applied, andthe shift lever is in the D or N setting. Thus, no power is transmittedbetween the pulley 10 and the engine 1. In this state, electromagneticclutch 191 can be brought to a connected state to allow M/G 300 tooperate the oil pump 194 while engine 1 is off. This is because thestarting clutch (not shown) disposed in the A/T 2 is arranged to beimmediately engaged for driving the vehicle smoothly upon re-starting ofthe engine.

In the case where the air conditioner and the power steering arerequired to be operated even if the engine 1 is stopped, controller 500applies to inverter 400 a switching control signal to rotate the M/G 300at the speed and torque corresponding to the loads of the pump P for apower steering unit, the compressor A/C for the air conditioner and theoil pump 190 for the A/T 2. In this case brake 41 is OFF or disengaged.

When the engine 1 is re-started from a state where the vehicle isstopped, M/G 300 in motor mode cranks engine 1 when brake coil 41 isturned ON thereby stopping rotation of sun gear 18. Brake coil 41 isenergized causing pulley 10 to rotate at a predetermined speed andtorque. Thus, the rotational force of M/G 300 is transmitted at adecreased speed from the ring gear 17 to the carrier 11 and thereby topulley 10 and thereby to crankshaft pulley CR.

When the M/G 300 is used as an electric generator, and/or theaccessories are operated while engine 1 is operating in a first runningmode, brake coil 41 is turned OFF and one-way clutch 22 is in an engagedstate. Thus, M/G 300 and the pulley 10 are rotationally connected witheach other so that the rotations of pulley 10 are transmitted throughclutch 22 to the M/G 300 via shaft 31.

When the pump P and the compressor A/C are operated by M/G 300 in motormode while engine 1 is stopped, brake coil 41 is turned OFF. In thissecond running mode engine 1 is stopped and pinion gears 15 and sun gear18 rotate freely. Carrier 11 and pulley 10 do not rotate because theyare engaged with belt B1 which is engaged with stopped crankshaft pulleyCR. Since brake 41 is OFF, sun gear 18 rotates in a direction oppositethat of ring gear 17 and pulley 30. In effect, this configuration actsas though the transmission 100 in placed in a ‘neutral’ gear therebypreventing transmission of torque from pulley 30 to pulley 10.

Transmission 100 is operating in part as a clutch to controltransmission of torque to the engine, or to receive torque from theengine depending on the mode selected.

FIG. 14 is a schematic of the inventive transmission in an alternategenerator motor arrangement. Generally, the components and theirrelationship in this alternate embodiment are as described in FIG. 13,with the differences described herein.

In this alternate embodiment M/G 300 is not directly attached totransmission 100. Transmission 100 has no directly connected accessory.M/G 300 is connected to transmission 100 by belt B2. Torque istransmitted to and from transmission 100 by belt B1 and B2 betweenengine 1, M/G 300 and the accessories. Transmission 100 is directlymounted to engine 1 using fasteners such as bolt or screws.

This embodiment illustrates that the M/G can be connected, eitherdirectly or by belt, to either end of transmission output shaft 31. Thisprovides alternate belt drive arrangements in which the inventivetransmission can be successfully used.

In operation, when the engine 1 is re-started from a state where thevehicle is stopped at a stop light for example, M/G 300 in motor modecranks engine 1 through belt B2, transmission 100, and belt B1 whenbrake coil 41 is turned ON, thereby engaging the brake and stoppingrotation of sun gear 18. Energizing brake coil 41 causes pulley 10 torotate at a predetermined speed and torque. Thus, the rotational forceof M/G 300 is transmitted at a decreased speed through belt B2, topulley 30 to ring gear 17 to the carrier 11 and thereby to pulley 10 andthereby to crankshaft pulley CR through belt B1. Due to theconfiguration of belt B2, accessories P and A/C are rotated while theM/G 300 is operating in motor mode during engine start as well.

When the M/G 300 is used as an electric generator, and/or theaccessories are operated while engine 1 is operating in a first runningmode, brake coil 41 is turned OFF and one-way clutch 22 is in an engagedstate. Thus, pulley 30 and pulley 10 are directly connected with eachother so that the rotations of pulley 10 are transmitted to pulley 30and thereby to the accessories P, A/C and M/G 300 through belt B2.

When the pump P and the compressor A/C are operated by M/G coil 41 isturned OFF. In this second running mode engine 1 is stopped and piniongears 15 and sun gear 18 rotate freely. Carrier 11 and pulley 10 do notrotate because they are engaged with belt B1 which is engaged withstopped crankshaft pulley CR. Since brake 41 is OFF, sun gear 18 rotatesin a direction opposite that of ring gear 17 and pulley 30, therebyallowing M/G 300 to operate accessories P and A/C through belt B2without also starting engine 1.

In yet another alternate embodiment, an accessory 1000 may be directlycoupled to transmission 100 as described in FIG. 11. Accessory 1000 maycomprise a fuel pump, oil pump or any other accessory as may be requiredby an engine or vehicle. In this embodiment accessory 1000 is directlyconnected to transmission 100 and to shaft 31. Due to the uniquearrangement of coaxial shafts 31, 200 of transmission 100, accessory1000 is fully operable by M/G 300 along with the other accessories evenwhen engine 1 is not operating and M/G 300 is in motor mode. Of course,accessory 1000 is also driven by engine 1 along with accessories P andA/C when engine 1 is operating and M/G 300 is operated as a generator.

Although forms of the invention have been described herein, it will beobvious to those skilled in the art that variations may be made in theconstruction and relation of parts without departing from the spirit andscope of the invention described herein.

1. A two speed transmission comprising: a planetary gear traincomprising an input member connected to an input carrier, the inputcarrier connected to an input shaft; a sun gear and a ring gear; theinput carrier comprising a plurality of planetary members each inmeshing engagement with the sun gear and the ring gear; the sun gearconnected to a brake member; the ring gear connected to an outputmember; and a one-way clutch operably disposed between the input shaftand the output member.
 2. The two speed transmission as in claim 1,wherein the input member comprises a pulley.
 3. The two speedtransmission as in claim 1, wherein the output member comprises apulley.
 4. The two speed transmission as in claim 3, wherein theplanetary gear train is substantially disposed within an output memberwidth.
 5. The two speed transmission as in claim 2, wherein the brakemember is substantially disposed within an input member width.
 6. Thetwo speed transmission as in claim 3, wherein the output member furthercomprises means for direct connection to an accessory.
 7. The two speedtransmission as in claim 1, wherein the input member and the outputmember are coaxial.
 8. The two speed transmission as in claim 1 whereinthe brake is electromagnetic.
 9. The two speed transmission as in claim1 further comprising: a bearing disposed between the brake and the inputshaft; and a bearing disposed between the sun gear and the input shaft.10. An accessory belt drive system comprising: a driver pulley; aplanetary gear transmission having an input pulley and an output pulley;the input pulley connected to an input carrier; an accessory having anaccessory pulley; a first belt drivingly engaged between the driverpulley and the input pulley; a second belt drivingly engaged between theoutput pulley and the accessory pulley; the output pulley and theaccessory pulley having a pulley ratio; the planetary gear transmissionhaving a transmission ratio, the transmission ratio determined by anengine speed; and the pulley ratio combined with the transmission ratiodetermining an accessory speed.
 11. The system as in claim 10, whereinthe transmission ratio greater than 1 is in the range of approximately1.3 to 1.7.
 12. The system as in claim 10, wherein the output pulley andinput pulley are coaxial.
 13. The system as in claim 10, wherein thesystem further comprises an accessory directly connected to atransmission output shaft.
 14. The system as in claim 10, wherein theplanetary gear transmission comprises an electromagnetic brake forcontrolling a sun gear rotation.
 15. The system as in claim 14, whereinthe planetary gear transmission comprises a bearing disposed between theelectromagnetic brake and an input shaft, the input shaft connected tothe input carrier.
 16. The system as in claim 15, wherein the planetarygear transmission comprises a sleeve bearing disposed between the inputshaft and the output shaft.
 17. The system as in claim 14, wherein theplanetary gear transmission comprises a one-way clutch disposed betweenan input shaft and an output shaft, said one-way clutch engaged when theelectromagnetic brake is disengaged.
 18. The system as in claim 14,wherein the electromagnetic brake is activated by an engine speedsignal.
 19. The system as in claim 16, wherein the planetary gears arefully contained within a width of a pulley.
 20. The system as in claim10, wherein the first belt has a modulus in the range of approximately1,500 N/mm to approximately 3,000 N/mm.
 21. The system as in claim 10,wherein the second belt has a modulus in the range of approximately1,500 N/mm to approximately 3,000 N/mm.
 22. The system as in claim 10further comprising a tensioner, the tensioner having asymmetric damping.23. A method of driving an engine accessory comprising the steps of:selecting a transmission output pulley and an accessory pulley to have apulley ratio; driving a transmission input pulley with a belt connectedto a driver; driving the accessory pulley with a belt connected to thetransmission output pulley; and driving the accessory at a firstaccessory speed at a first engine speed; driving the accessory at asecond accessory speed at a second engine speed, the second accessoryspeed is less than the first accessory speed, the first engine speed isless than a second engine speed; controlling the transmission ratio withan engine speed; using a transmission ratio greater than 1 at the firstengine speed; using a transmission ratio equal to 1 at the second enginespeed; and controlling the accessory speed with a transmission ratio andthe pulley ratio.
 24. The method as in claim 23 further comprising thestep of damping a belt oscillation asymmetrically.
 25. The method as inclaim 23 further comprising the step of connecting an accessory directlyto the transmission.
 26. An accessory belt drive system comprising:transmission means having a transmission ratio and an input means and anoutput means; the transmission means driven by a driver engaged throughthe input means; the output means drivingly connected to a firstaccessory drive means; the output means and the first accessory drivemeans having a ratio; a second accessory directly connected to thetransmission means; the transmission ratio and the ratio combined drivethe first accessory at a first speed for a first driver speed; thetransmission ratio disengagable at a second driver speed, the seconddriver speed greater than the first driver speed.
 27. The accessory beltdrive system as in claim 26, wherein the transmission means comprises anelectromagnetic brake means for controlling the transmission ratio. 28.A two speed transmission comprising: an input means; an output means;the input means and the output means coaxially disposed; a planetarygear means disposed between the input means and the output means; anelectromagnetic brake means connected to a sun gear means; a one-wayclutch means disposed between the input means and the output means; andthe one-way clutch means is engaged when the electromagnetic brake meansis disengaged.
 29. A method of driving a belt driven engine accessorycomprising: driving a transmission with a driver; driving an accessorywith the transmission; determining a pulley ratio between the accessoryand the transmission; selecting a transmission ratio according to adriver speed; operating the accessory with the combination of the pulleyratio and the transmission ratio at a first driver speed; and operatingthe accessory solely with the pulley ratio at a second driver speed,wherein the second driver speed is greater than the first driver speed.30. The method as in claim 29 further comprising: connecting a secondaccessory directly to the transmission.
 31. A power train system for avehicle comprising: an engine operable in a first and second runningmode; a motor generator; an accessory that receives power from the motorgenerator when the engine is operating in the second running mode; aclutch between the motor generator and the engine; a sensor operable todetect a vehicle operating condition and operable to produce a signal; acontroller using the signal to selectively activate the first runningmode or second running mode; and the controller operates the motorgenerator to supply power to the accessory during the second runningmode while disabling the clutch to prevent power from being transferredfrom the motor generator to the engine when the engine is operated inthe second running mode.
 32. The power train system as in claim 31further comprising: an accessory operated either by said engine or saidmotor generator, wherein said accessory is connected to a rotationalshaft of said motor generator.
 33. The power train system as in claim31, wherein: the motor generator is connected to a drive shaft of theengine; a transmission mechanism is disposed between the engine and themotor generator, the transmission mechanism capable of transmittingrotation of a rotational shaft of said motor generator to the driveshaft of said engine at a changed speed; the accessory is connected tothe rotational shaft of said motor generator and is operated by saidengine or said motor generator; and said transmission mechanism reducesthe speed of rotation of the rotational shaft of said motor generatorand transmits the rotation to the drive shaft of said engine when saidaccessory is operated by said motor generator in a state where saidengine is stopped.
 34. The power train system as in claim 33, whereinsaid clutch interrupts transmission of rotation of the rotational shaftof said motor generator to the drive shaft of said engine when theaccessory is operated by said motor generator in a state where saidengine is stopped.
 35. The power train system as in claim 32, whereinthe signal is digital.
 36. The power train system as in claim 32,wherein the signal is analogue.
 37. A method for operating a power trainsystem for a vehicle including an engine operable in a first runningmode or a second running mode, an electrically powered motor generator,an accessory that receives power from at least one of the engine and themotor generator, and a transmission between the engine and the motorgenerator, the method comprising: detecting a vehicle operatingcondition with a sensor; providing a signal from the sensor; using thesignal to selectively activate the first running mode or the secondrunning mode; supplying power to the accessory from the motor generatorwhen the second running mode is selected; and disabling the clutch toprevent power from being transferred from the motor generator to theengine when the engine is operated in the second running mode.
 38. Themethod as in claim 37 comprising providing a digital signal.
 39. Themethod as in claim 37 comprising providing an analogue signal.
 40. Themethod as in claim 37 comprising attaching the accessory to thetransmission.
 41. The power train system as in claim 33, wherein theaccessory is directly connected to the transmission.
 42. The power trainsystem as in claim 33, wherein the motor generator is directly connectedto the transmission.
 43. The power train system as in claim 41, whereinthe motor generator is connected to the transmission with a belt. 44.The system as in claim 10, wherein the planetary gear transmission has aduty cycle of approximately 5% to 25%.
 45. The method as in claim 23comprising the step of operating at a transmission duty cycle in therange of approximately 5% to 25%.
 46. The system as in claim 26, whereinthe transmission means has a duty cycle in the range of approximately 5%to 25%.
 47. The method as in claim 29 comprising the step of operatingthe transmission with a duty cycle of approximately 5% to 25%.